1 /*
2 * EL4J, the Extension Library for the J2EE, adds incremental enhancements to
3 * the spring framework, http://el4j.sf.net
4 * Copyright (C) 2005 by ELCA Informatique SA, Av. de la Harpe 22-24,
5 * 1000 Lausanne, Switzerland, http://www.elca.ch
6 *
7 * EL4J is published under the GNU Lesser General Public License (LGPL)
8 * Version 2.1. See http://www.gnu.org/licenses/
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU Lesser General Public License for more details.
14 *
15 * For alternative licensing, please contact info@elca.ch
16 */
17
18 package ch.elca.el4j.services.exceptionhandler.handler;
19
20 import org.aopalliance.intercept.MethodInvocation;
21 import org.slf4j.Logger;
22 import org.springframework.aop.target.HotSwappableTargetSource;
23
24 import ch.elca.el4j.services.exceptionhandler.AbstractExceptionHandlerInterceptor;
25 import ch.elca.el4j.services.exceptionhandler.InappropriateHandlerException;
26 import ch.elca.el4j.services.exceptionhandler.RetryException;
27
28 /**
29 * This class simplifies the implementation of exception handlers that use
30 * another implementation with the same interface to fulfil the callers
31 * invocation.
32 *
33 * @svnLink $Revision: 3873 $;$Date: 2009-08-04 13:59:45 +0200 (Di, 04. Aug 2009) $;$Author: swismer $;$URL: https://el4j.svn.sourceforge.net/svnroot/el4j/branches/el4j_3_1/el4j/framework/modules/exception_handling/src/main/java/ch/elca/el4j/services/exceptionhandler/handler/AbstractSwappableTargetExceptionHandler.java $
34 *
35 * @author Andreas Bur (ABU)
36 * @see ch.elca.el4j.services.exceptionhandler.handler.AbstractReconfigureExceptionHandler
37 */
38 public abstract class AbstractSwappableTargetExceptionHandler extends
39 AbstractRetryExceptionHandler {
40
41 /** The TargetSource to change the target on. */
42 private HotSwappableTargetSource m_swapper;
43
44 /**
45 * Sets the TargetSource that is used in the proxy, where the target has to
46 * be swapped.
47 *
48 * @param swapper
49 * The TargetSource to set.
50 */
51 public void setSwapper(HotSwappableTargetSource swapper) {
52 m_swapper = swapper;
53 }
54
55 /**
56 * {@inheritDoc}
57 */
58 protected Object retry(Throwable t,
59 AbstractExceptionHandlerInterceptor exceptionInvoker,
60 MethodInvocation invocation, Logger logger)
61 throws InappropriateHandlerException, RetryException {
62
63 try {
64 Object newTarget = getNewTarget(
65 m_swapper.getTarget(), t, invocation, logger);
66 m_swapper.swap(newTarget);
67
68 } catch (InappropriateHandlerException ihe) {
69 throw ihe;
70 } catch (Throwable nt) {
71 throw new RetryException(getRetries());
72 }
73
74 throw new RetryException(getRetries(), m_swapper);
75 }
76
77 /**
78 * Determines a new target to be used by the proxy.
79 *
80 * @param current
81 * The current target which the proxy is working on.
82 *
83 * @param t
84 * The exception that caused this strategy. Subclasses may distinguish
85 * between different exception types.
86 *
87 * @param invocation
88 * The original invocation that failed.
89 *
90 * @param logger
91 * The logger.
92 *
93 * @return Returns an alternative bean that implements the same interface
94 * as the original one.
95 *
96 * @throws RetryException
97 * Signals that the complete invocation has to be rerun.
98 *
99 * @throws Throwable
100 * Whenever something goes wrong.
101 */
102 protected abstract Object getNewTarget(Object current, Throwable t,
103 MethodInvocation invocation, Logger logger)
104 throws RetryException, Throwable;
105 }